Oxygen lance with slag-breaking means



y 1968 R. KEMMETMUELLER 3,385,586

OXYGEN LANCE WITH SLAG BREAKING MEANS Filed Feb. 12, 1965 m M R a 3 w 0 u v E T M N N .I R E 5 O V M "H m M 6 A o z H TH HMH HHHHM 3 0 v 2 M B 0 A a P United States Patent 3,385,586 OXYGEN LANCE WITH STAG-BREAKING MEANS Roland Kemmetmueller, Pittsburgh, Pa., assignor to Waagner-Biro AG, Vienna, Austria Filed Feb. 12, 1965, Ser. No. 432,281 7 Claims. (Cl. 266-34) ABSTRACT OF THE DISCLOSURE An oxygen lance which is adapted to extend into a converter for directing oxygen into the latter. The oxygen lance includes an elongated tubular means which has a bottom end for directing oxygen into the converter from the region of the bottom end of this tubular means, A slag-breaking means is carried by the elongated tubular means at the exterior thereof and at a substantial distance higher than the bottom end thereof for breaking slag which tends to accumulate on the exterior of the tubular means, so that the broken slag falls from the tubular means to prevent excessive accumulation of slag thereon. The slag-breaking means includes a plurality of ribs which are fixed to and extend longitudinally of the tubular means at the exterior thereof, and these ribs are distributed about the axis of the tubular means while being angularly spaced from each other about the latter axis by less than 180 so that the slag cannot extend around the tubular means to an extent sufficient to enable the slag to shrink onto the tubular means. Therefore when the slag shrinks it will simply fall from the exterior surface of the tubular means.

The present invention relates to the manufacture of steel! More particularly, the present invention relates to structure adapted to be used with converters, particular 1y of the basic oxygen type.

In particular, the present invention relates to an oxygen lance for use with a converter of the above type as well as structure which cooperates with the oxygen lance.

As is well known, in the manufacture of steel with a basic oxygen converter an oxygen lance extends into the converter for directing oxygen onto the molten metal in the interior of the converter. The discharge 'end of the oxygen lance is located relatively close to the bath of metal and the jet of oxygen displaces the slag and provides a spray of slag which unavoidably becomes deposited on the exterior of the lance. This slag which thus becomes deposited on the exterior of the lance solidifies and shrinks thereon subjecting the lance itself to undesirable stresses resulting from the shrinking slag which compresses the lance. However, of even greater significance is the fact that the accumulated slag which shrinks onto the exterior of the lance prevents removal thereof from the opening through the hood which is situated over the converter, with a result that it often becomes necessary to cut through the lance in order to enable the latter to be separated from the remaining structure, and of course the life of such lances is very limited.

'It is accordingly a primary object of the present invention to provide a lance which will reliably avoid excessive accumulation of slag on its exterior surface so that there will be no problem in removal of the lance when the operations are to be terminated.

In addition, it is an object of the present invention to provide for an oxygen lance a structure which will direct the oxygen through the slag in a manner which will reduce the extent of spraying of slag onto the lance itself.

An additional object of the present invention is provided for a lance of the above type a simple rugged 3,385,586 Patented May 28, 1968 structure carried by the exterior of the lance to reliably prevent excessive accumulation of slag thereon.

Furthermore, it is an object of the present invention to provide a structure which will condition the exterior surface of the lance in a manner which will deter excessive slag accumulation on the exterior surface of the lance.

Also, it is an object of the invention to provide a structure which will very effectively cool a lance.

Primarily, the oxygen lance of the invention includes an elongated tubular means which is adapted to direct oxygen into the interior of a converter, and this elongated tubular means is provided, in accordance with the invention, with a slag-breaking means carried by the elongated tubular means at its exterior and functioning to break the slag as the latter shrinks so as to cause the slag to fall from the lance instead of accumulating thereon. In addition, the structure of the present invention is adapted to spray onto the exterior of the lance a coating of graphite which will also deter excessive accumulation of slag on the exterior surface of the lance. Finally, the discharge end of the tubular means of the lance of the invention is provided with a nozzle structure which in accordance with the invention will direct a plurality of jets of oxygen onto the molten metal in a manner which will on the one hand improve the operation of the converter itself and which will on the other hand prevent the slag from spraying onto the lance to the same extent as is encountered with conventional lances.

The invention is illustrated by way of example in the accompanying drawings which form part of the application and in which:

FIG. 1 is a schematic side elevation fragmentarily illustrating how a lance extends through a hood into the upper end of a converter, FIG. 1 schematically illustrating structure for spraying graphite onto the exterior surface of the lance;

FIG. 2 is a fragmentary sectional plan view taken along line 2-2 of FIG. 1 in the direction of the arrows;

FIG. 3 is a partly broken away fragmentary side elevation, on an enlarged scale as compared to HQ. 1, illustrating one possible embodiment of a lance according to the present invention;

FIG. 4 is a bottom plan view of the lance of FIG. 3;

FIG. 5 is a transverse section, on an enlarged scale as compared to FIGS. 3 and 4, taken along line 5-5 of FIG. 3 in the direction of the arrows and showing in particular the details of the slag-breaking means of the invention;

FIG. 6 is a sectional elevation taken along line 6--6 of FIG. 4 in the direction of the arrows and showing the interior details of the lance of the invention at the discharge end thereof; and

FIG. 7 is a fragmentary sectional plan view of a structure which may be used in place of that shown in FIG. 2.

Referring now to the drawings, FIG. 1 shows the upper end of a conventional basic oxygen converter 10. An oxygen lance 12 is supported in a known way extending downwardly through the open top of the converter 10 into the interior thereof for providing a stream of oxygen which is directed onto the molten metal at the bottom of the converter. The oxygen is supplied to the lance 12 in a known manner and in addition the lance 12 communicates with a suitable cooling fluid, such as water, also in a known manner. Arranged over the converter 10 is a hood 14 into which the gas issuing through the top of the converter 10 flows, this gas being conducted away from the hood 14 in a well known manner which does not form part of the present invention.

One of the features of the present invention resides in providing the exterior surface of the lance 12 with a graphite coating which will deter the clinging of slag to the exterior surface of the lance 12, and this feature may simply take the form of a suitable structure which may be operated to brush onto the exterior surface of the lance 12 a liquid such as water in which particles of graphite are suspended. As soon as this film of Water with particles of graphite therein reaches the interior of the hood 14 the water evaporates to leave on the exterior surface of the lance 12 a film of graphite which renders the exterior surface of the lance 12 far less receptive to the adherence of a coating of slag on the exterior surface of the lance than if there were no graphite coating on the lance 12.

While it is possible to simply brush a liquid with particles of graphite suspended therein onto the exterior surface of the lance 12, the arrangement shown in FIGS. 1 and 2 is preferred. The means shown in FIGS. 1 and 2 for applying to the exterior surface of the lance 12 a coating of graphite includes a tank 16 in which a supply of water with graphite particles suspended therein is situated. This tank 16 communicates through a pipe 18 with a circular pipe 20 which is mounted on the open top end of a tubular inlet 22 through which the lance 12 is introduced into the interior of the hood 14 in the manner indicated in FIG. 1. The pipe 18 carries a valve 24 which may be manually operated or which may be electrically operated through a suitable solenoid which may be energized and deenergized by the operator, and when the valve 24 is open the liquid will fiow from the tank 16 into the circular pipe 20. As is shown most clearly in KG. 2, this pipe 20 is provided along its inner periphery with a plurality of outlet nozzles 26 through which the liquid, with graphite particles suspended therein, is sprayed onto the exterior surface of the lance 12, and the valve 24 is opened during introduction of the lance 12 through the tubular inlet 22 of the hood 14 so that the lance is uniformly covered over its exterior surface with the liquid which carries the particles of graphite. It should be noted that it is not possible to provide this coating after the lance has been introduced because the liquid will only flow down from the tube 20 along the exterior surface of the lance 12 through a relatively short distance before it evaporates due to the heat within the hood 14. Therefore, simultaneously with the introduction of the lance 12 into the converter a film of graphite is applied to the exterior surface of the lance 12, and this graphite film will reliably deter to a very large extent the clinging of excessive slag to the exterior surface of the lance 12.

In order to brush an aqueous solution of graphite onto the exterior of the lance an arrangement as shown in FIG. 7 may be used. The pipe 78 corresponds to the pipe 18 and delivers the solution to the tubular ring 70 which replaces the ring and which has discharge openings 76 at its inner periphery. In addition the tube 70 carries bristles 71 which distribute the solution onto the surface of the lance 72 which engages the inner tips of the bristles, this lance 72 having the same structure as the lance 12.

The details of the lance 12 are illustrated in FIGS. 3-6. Thus, this lance 12 is in the form of an elongated tubular means which includes an outer tube 28 having a curved discharge end 30. Within the outer tube 28 is located an inner double-walled tube 32 having an inner tubular portion 34 and an outer tubular portion 36, these tubular portions being connected directly to each other in the manner shown in FIG. 6 at the region of the discharge end of the tubular means. The lance 12 also includes discharge nozzles 38 in the form of tubes which respectively provide communication between the interior of the inner double-walled tube 32 and the exterior of the outer tube 28 at the discharge end 30 thereof. Thus, these nozzles 38 have outer open ends 40 through which oxygen will discharge, and in accordance with a further feature of the invention the nozzles 38 are angularly distributed uniformly about the common axis of the tubes which form the lance 12. In the illustrated example there are three nozzles 38 which are spaced from each other by about the common axis of the tubes, so that with the lance of the invention there will be three jets of oxygen issuing simultaneously from the discharge end 30 in different directions through the slag into the molten metal therebeneath, and as a result of this feature there is on the one hand less of a slag spray thrown up against the exterior surface of the lance and on the other hand a far better application of the oxygen to the molten metal so that the reaction with the oxygen is also enhanced because of the better distribution of the oxygen resulting from the plurality of nozzles 38 of the invention.

In accordance with a further feature of the invention the exterior surface of the tubular means which forms the lance 12 carries a slag-breaking means 42 which cooperates with the graphite coating to contribute to the prevention of accumulation of excessive slag on the exterior of the tubular means. This slag-breaking means 42 of the invention includes a plurality of elongated ribs 44 which extend longitudinally of the lance 12 at its exterior and which are also uniformly distributed about the axis of the lance 12. As is apparent from FIG. 3, the ribs 44 extend throughout the length of that portion of the lance which is likely to have slag thrown thereagainst, and inasmuch as the immediate region of the discharge end 30 of the lance will not be contacted with the slag spray the ribs 42 terminate short of the discharge end 30 of the lance. As is shown most clearly in FIG. 5, the ribs 44 are of a substantially V-shaped cross section and have their crest edges situated distant from the tubular means which forms the remainder of the lance of the invention. These ribs 44 may be made of copper and may be fixed to the exterior surface of the tube 28 as by being welded thereto with bronze weldments 46. In the example illustrated in the drawings there are five ribs 44 uniformly distributed about the axis of the lance and extending parallel to the axis. Because these slag-breaking ribs 44 are angularly spaced from each other by less than any slag which clings to the exterior surface of the tube 28' cannot extend around the axis of the lance through more than 180. The slag, as it solidifies, shrinks, and because of the fact that the extent of circumferential gripping of the lance by the solidifying slag is limited with the ribs 44, the shrinking slag simply falls from the exterior surface of the lance so that in this way the slag-breaking means 42 reliably prevents the accumulation of excessive slag on the exterior surface of the lance 12.

As may be seen from FIG. 6, a suitable cooling fluid such as water flows toward the discharge end 30 of the lance in the interior thereof through the inner passage 46 formed by the inner tubular portion 34 of the doublewalled tube 32, and the cooling liquid flows from the inner passage 46 along an outer passage 48 which is defined between the inner tube 32 and the outer tube 28 of the lance. The interior 50 of the inner tube 32 is supplied with oxygen which flows through the nozzles 38 to the exterior of the lance through the outlets 40 in the manner described above.

In an actual example of a lance constructed in accordance with the invention, the tubes 28 and 32 were made of steel having a thickness of A1 inch. The outer diameter of the lance was approximately one foot while the diameter of the tube 36 was on the order of 10 inches and the diameter of the tube 34 was on the order of 5 inches. Each of the ribs 44 was provided with a radial width of 1 and inch.

The ribs were coextensively arranged along the exterior surface of the tube 28 and each had a length of approximately 10 feet while somewhat more than 3 feet was allowed to remain without ribs from the discharge end of the lance to the ends of the ribs nearest the discharge end 30. This lance of the invention was found to operate in an extremely satisfactory manner to prevent accumulation of excessive slag on the exterior surface of the lance. In addition, the ribs 44 were found to have in combination with the cooling water a very effective cooling action which maintained the wall of the tube 28 at its region between the ribs at a temperature of between 80 and 100 F. during actual operation.

It should be noted that the bottom end portion of the lance is made of steel, in contrast to conventional lances where a metal such as copper must be used at the bottom end of the lance. The bottom end portion of the lance is initially in the form of a separate unit made of steel and welded onto the remainder of the lance. Thus, the doublewalled tube 32 may include a separate lower portion made of steel and welded at its inner and outer walls to the remainder of the tube 32. Thereafter the outer tube 28 has its separate lower steel portion welded onto the remainder of the outer tube 28, and the nozzles 38 are then assembled with the inner and outer tubes.

The features sought to be protected are set forth in the following claims:

1. An oxygen lance comprising elongated tubular means having a bottom end portion and adapted to extend into a converter for directing oxygen into the latter from the region of said bottom end portion of said tubular means, and slag-breaking means carried by said elongated tubular means at the exterior thereof at a substantial distance higher than said bottom end portion at an exterior region of said tubular means against which slag is thrown during operations in the converter for breaking slag which tends to accumulate on the exterior of said tubular means so that the broken slag falls from said tubular means to prevent excessive accumulation of slag thereon.

2. A lance as recited in claim 1 and wherein said slagbreaking means includes a plurality of ribs fixed to and extending longitudinally of said tubular means at the exterior thereof, said ribs being distributed about the axis of said tubular means and being spaced from each other by less than 180 about said axis so that slag cannot completely surround and shrink onto said tubular means, whereby the slag upon shrinking will fall from the exterior surface of said tubular means.

3. A lance as recited in claim 2 and wherein said ribs are made of metal and have a tapered substantially V- shaped cross section provided with a crest which is situated distant from said tubular means.

4. A lance as recited in claim 3 and wherein said ribs are made of copper.

5. A lance as recited in claim 4 and wherein said copper ribs are welded by bronze Weldments to said exterior surface of said tubular means.

6. An oxygen lance comprising an elongated outer tube having a discharge end, an inner, double-walled tube arranged coaxially Within and spaced from said outer tube to define an outer passage therewith, said double-walled tube including an inner tubular portion defining an inner passage which communicates at said end of said outer tube with said outer passage and through which a cooling fluid is adapted to flow from said inner passage to said outer passage, and said inner tube having in addition to said inner tubular portion and outer tubular portion which is fixed to said inner tubular portion at the region of said discharge end of said outer tube and which defines with said inner tubular portion a space through which oxygen is adapted to flow, a plurality of tubular nozzles each communicating at one end with the interior of said inner tube between said inner and outer tubular portions thereof at the region of said discharge and of said outer tube and at an opposite end with the exterior of said outer tube at said discharge end thereof so that oxygen will fiow from the interior of said inner tube through said nozzles to the exterior of said outer tube at said discharge end thereof, and slag-breaking means carried by said outer tube at the exterior thereof at an elevation substantially higher than said discharge end of said outer tube at a region of the exterior thereof against which slag is thrown during operation of the lance for preventing excessive accumulation of slag at the exterior of said outer tube.

7. A lance as recited in claim 6 and wherein said slagbreaking means includes a plurality of elongated metallic ribs fixed to and extending longitudinally of said outer tube, said ribs being angularly spaced from each other, about the common axis of said tubes, by less than so that slag shrinking onto the exterior surface of said outer tube cannot grip the latter and Will instead break and fall from the exterior surface of said outer tube.

References Cited UNITED STATES PATENTS 1,718,757 6/1929 Morris.

1,849,814 3/1932 Woodruff 239132.5 2,820,707 1/1958 Walker 266-35 X 3,082,997 3/1963 Kurzinski 26634 3,108,022 10/ 1963 Church.

3,170,016 2/1965 Grace 26634 3,224,749 12/1965 Berry 26634 1. SPENCER OVERHOLSER, Primary Examiner.

E. MAR, Assistant Examiner. 

